The source of this information is from Dr Bernstein :
If you have ever seen a man with Class VII balding, and we all have, you have seen a graphic representation of the limits and confines of the donor area. This is the hair zone that is considered permanent. With rare exceptions, this rim of hair remains even in the most advanced cases of male pattern baldness. The boundaries of this zone extend from in front of the ears, around the temples, and to the back of the head (figure 1). The hair at the temples may recede back toward the ear, and the balding area of the crown may dip quite low into the occipital area, at the back of the head. We must always assume that any man considering hair transplant surgery will eventually advance to this Class VII level for balding; its easy to understand why. Visible scars may be revealed if the baldness advances, and donor tissue has been taken too high, too low, or too far in front of the ears.
Another problem involving scarring in the donor area is that of the widened scar. In a patient without a systemic disease or drug use that retards healing, a well-closed, non-infected incision should eventually appear as a thin white line, well camouflaged by the hair. Sometimes, however, this is not the case. For example, if the donor strip is taken too low in the back of the head (toward the top if the neck), a widened scar can result. Often, as men get older, the inferior hairline (at the neck) will move higher. If this is the case, a low, widened scar can be a cosmetic liability.
In addition, certain patients with an inborn weakness of collagen or defects in the building of new collagen (collagen is the connective tissue protein of which ligaments, tendons and scars are made) may develop wider than normal scars regardless of how well the incision is closed. Surgical wisdom has always taught us that closure of any wound under tension (such as a wide incision or in taut tissues) can lead to a widened scar. Therefore, we always attempt to make the donor strip as narrow as we can, based on the tightness or laxity of the patients scalp. Indeed, this is one of the problems seen after scalp reductions and/or multiple transplant procedures: a tight, unyielding, fibrotic donor area. This is why hair restoration surgeons like to see patients with lax, loose scalps.
Occasionally, though, a paradox exists. This is when patients who do have scalp laxity heal with widened scars. It is possible that these patients may have one of the aforementioned collagen defects. In short, careful evaluation and planning can result in fine, cosmetic scars in most cases; there are cases where the scar is sub-optimal regardless of the surgeons skill.
Many of us today see the results of older methods of donor harvesting; often, patients with the older, “pluggy” look of the past seek transplantation to remove or disguise the old round grafts, or their balding may have progressed to the point that they desire grafting to newly bald areas. When the outmoded harvesting techniques of punch grafting with open donor healing were used, the result was a “shotgun” or “moth-eaten” appearance that is cosmetically quite displeasing. This type of scarring also renders further strip harvesting difficult, to say the least, and it greatly complicates the estimation of needed strip size for a given number of grafts. Similar problems arise when the patients donor area has been subjected to multiple small strip harvests, with a “stairstep” pattern of linear scars, or extensive plug harvesting that was then sutured in a “semi-sawtooth” pattern.
We have spoken in previous sections about the necessity of preserving the donor area for possible future transplant work. Even if an individual is older, has seemingly “stable” baldness, and is satisfied with his hair transplant outcome, the day may arise when his hair loss accelerates. Then, if his donor area has been conserved, he may have sufficient reserves for additional procedures. If not, then his options are limited to camouflage, hairpieces, or living with the appearance of baldness.
We also discussed single strip harvesting as the technique with the most “hair-conserving” potential, and we deemed large sessions of follicular units as probably the most expedient and efficient method of transplantation. If these techniques are properly utilized, then the fewest hairs will be damaged at the time of harvesting. Furthermore, the integrity of the donor area will be preserved, scar
Minimizing the scar from the donor incision is a critical part of a successful hair transplant procedure. A fine donor scar allows a person to keep his/her hair relatively short after the hair restoration (if one wants to do so) and increases the amount of hair that can be harvested (removed) in subsequent hair transplant procedures.
A number of techniques have been developed to minimize donor scarring when using a strip excision during Strip surgery. These include the use of tumescent anaesthesia, undermining, absorbable sutures, buried sutures, staples and trichophytic closures. The technique of FUE where follicular units are removed directly from the scalp without a linear incision, is covered in another section.
Strip incisions are widely used because they enable the hair transplant surgeon to efficiently perform large hair transplant sessions, while at the same time, minimize damage to hair follicles. The reason this is possible is because the strip of donor tissue that is removed from the scalp is placed under a series of stereo-microscopes where the individual follicular units can be dissected from the tissue under direct visualisation.
There are four main aspects to having the donor incision heal in a fine line; 1) placing the incision in the proper location 2) using the correct donor strip dimensions, 3) removing the strip without damage to the tissue, and 4) closing the donor area with impeccable surgical techniques.
The ideal placement of the donor incision is in the mid-part of the permanent zone located in the back and sides of the scalp. This area lies in a band that starts above the occipital protuberance (the bump felt in the middle part of the back of the scalp) and extends to either side in a gentle, upward sloping curve that follows the contour of the scalp. If hair is harvested below this region, there is a greater risk of scarring from the wound stretching, since the incision will be too close to the muscles of the neck. If the incision is above this area, the hair may not be permanent and may fall out as the baldness progresses.
Although the length of the donor incision is determined predominantly by the number of follicular unit grafts required for the hair restoration, the width (height) of the donor incision depends upon the patient’s scalp laxity. This is a genetic attribute of the patient’s scalp that must be carefully measured by the hair transplant surgeon during the initial evaluation. With good scalp laxity, a wider strip may be harvested from the donor area without the risk of scarring (although patients with very loose scalps may be at increased risk of a wide scar. If the scalp is too tight, taking a normal size strip may be impossible.
If the strip width is too narrow, the incision will need to be unnecessarily long to obtain an adequate amount of donor hair. If the strip width is too wide, the risk of having a widened scar will be increased significantly. Expert clinical judgment, acquired over years of experience, is needed for the surgeon to consistently set the appropriate length and width of the donor strip and achieve the minimum possible scar.
Most patients have 90-100 follicular units per cm2 in their donor area. Therefore, in a hair transplant of 2,000 follicular unit grafts, a donor strip that was 1cm wide would need to be slightly over 20 cm long to yield the appropriate number of grafts.
In Follicular Unit Transplantation your physician will obtain donor hair from a long, thin strip removed from the back and/or sides of your scalp. The procedure can most easily be accomplished when the scalp is moderately loose as it enables the surgeon to harvest more grafts. A tight scalp can be loosened using the following simple exercise.
A major advancement in the removal of the donor strip is the use of tumescent anesthesia.Tumesce simply means to expand by injecting fluid into the tissues. In this technique, very dilute concentrations of anesthetic fluid are injected into the fat layer of the donor region of the scalp. This serves a number of purposes, the first is to decrease bleeding from the pressure of the fluid on small blood vessels (capillaries), the second is to firm the skin so that the incision can be more easily controlled and third, to increase the distance between the follicles and the deeper tissues of the scalp. This helps the surgeon keep the incision superficial so that the larger nerves and blood vessels in the scalp are not injured and so that the fascia is not cut. The fascia is a layer of fibrous tissue that lies just below the fat layer that gives support to the scalp. If this layer is cut, the risk of having a stretched scar significantly increases.
Undermining, the technique of separating the upper layers of the scalp from the lower portions in the area around the wound edges, can be useful if there is excessive tension on the wound edges during closure. This is occasionally needed when the scalp is tight, when a patient has had multiple prior hair transplant procedures or when the donor strip was too wide. Undermining, however, can increase the risk of bleeding, nerve injury and trauma to the scalp and may result in poor healing. Although undermining is a very useful tool in some situations, it is generally best to avoid the need for undermining entirely by carefully planning the donor incision.
The advantage of using staples is that, of all the donor closures, staples conserve the most hair. There are two main reasons for this. The first is that stainless steel staples are inert. This means that, unlike sutures, the body tissues do not react to them and therefore staples cause minimal inflammation (which has the potential to damage hair follicles). The second advantage of staples is that they are interrupted, in contrast to sutures which are used in a long running loop stitch. A running stitch had a tendency to strangle hair follicles, particularly if there is any swelling after the surgery. The use of interrupted staples avoids this potential damage to grafts.
The advantage of sutures had been that the surgeon had the most control in approximating (closing together) the wound edges. For a long time we felt that the better control of the wound edges offered by sutures outweighed its disadvantages. However, with new stapling techniques and modifying the time that the staples are left in the scalp, excellent wound edge approximation is achieved and the main advantage of sutures has largely been eliminated.
Sutures are generally more comfortable post-operatively than staples and are more convenient for patients because they do not need to be removed. However, because staples offer superior preservation of donor hair, this is our closure of choice for most procedures. For those patients who will benefit from sutures, or for those who simply prefer them, we still offer this type of closure.
In a trichophytic closure, the surgeon makes the initial incision parallel to the hair follicles and then trims away 1 to 3-mm of tissue of either the upper or lower wound edge (or both), so that the top of the hair follicles at that wound edge are removed. During the “tricho” closure, the trimmed wound edge is pulled towards the opposite edge so that the bottom parts of the cut hairs are pointing slightly towards the incision (rather than parallel to each other). The goal is that these hairs will eventually grow through the incision and thus decrease the visibility of the scar.
Trichophytic closures generally require the wound edges to be sutured, although it is possible to get benefit with a trichophytic closure when staples are used. We are currently studying this combination of a trichophytic closure with staples. The advantage of this type of trichophytic closure is that staples enable the maximum conservation of donor hair.
In the upper ledge trychophyic closure, the hair from the upper wound edge points down and grows into the scar.
In the lower ledge trychophytic closure, the hair in the lower wound edge grows through the overlapping upper edge.
Further information on Bernstein Medial’s Website here : Bernstein Medical website